1. Field of the Invention
The present invention relates to a piezoelectric element unit preferably used for such as a part of a driving device for driving a driven member and to a driving device therewith.
2. Description of the Related Art
Piezoelectric elements can mutually convert mechanical displacement to or from electronic displacement by utilizing piezoelectric effects or inverse piezoelectric effects. These piezoelectric elements are manufactured by molding and firing piezoelectric ceramics to obtain an element body, forming electrodes thereto, and further performing polarization treatment, for example.
Since the mechanical displacement obtained by the piezoelectric elements is comparatively small, the piezoelectric elements are preferably used as a driving device for which a precise and accurate control is required, for example. More specifically, the piezoelectric elements are used for lens drives, head drives of HDDs, head drives for ink jet printers, fuel injection valve drives, and the like.
For example, as a driving device with a piezoelectric element, one having a structure where a driving rod and a support table are respectively adhered to both ends of the piezoelectric element is disclosed (see Patent Literature 1 or so).
However, conventional multi-layered piezoelectric elements may be broken by a large load generated at the time of driving and so on or by some external force when they are particularly used for a purpose requiring a severe durability.    [Patent Literature 1] JP Patent Application Laid Open No. 2002-119074